For voice communication procedures like teleconferencing/videoconferencing when also using a headset with cellular phones or the like, voice quality is an important design criterion.
If conference participants are located in a loud environment, this can disrupt the conference. This can happen if the participant is taking part in the conference using a cell phone in public, but participants using a headset in a conference environment can also be affected. On the one hand, the participants in the loud environment find it more difficult to understand the content of the conference; on the other hand, the ambient noise is transmitted to the other conference participants. In addition, the participants in the loud environment cannot hear their own voices well, which makes them have to speak louder to overcome the ambient noise. This can cause at least two other disadvantages. For one, speaking louder can result in additional noise, which can be disruptive at the location of the other participant, e.g., in an open-plan office (in an environment with many conference participants, this can also result in everyone attempting to speak louder than the others, and the noise level building up accordingly). For another, it is difficult to discuss confidential and/or commercial matters in publicly accessible buildings or publicly accessible locations, since basically anyone in the vicinity can listen in. The participant's auditory impression can also be disrupted if the speaker's own voice is played back to him or her out of the conference system with a certain delay (i.e., “round trip delay”). Echo and hall effects can be created, for example, if the voice signal is output by the conference system via a speaker and picked up by a microphone (acoustic echo), or if signals are simultaneously sent and received by telecommunication equipment (duplex echo). An echo and the resulting disruption gets stronger the louder the participant speaks.
To minimize the disruption caused to other participants by a participant speaking too loud, it is common for a conference moderator or the participant to manually lower the sound level of the line with the loud environment (i.e., “muting”). This is often a repetitive procedure, and it might have to be adjusted multiple times or constantly.
To handle disruptive ambient noise, it is common, e.g., for teleconferencing, to output to the ear's speaker the ambient noise phase shifted by 180° in addition to the conference signal. This cancels out the ambient noise for the ear. Similar solutions have also been developed for listening to music on a plane or in a train car, or for aircraft or helicopter pilot headsets. In the best case, the environment can barely be heard. However, the participant's voice can also barely be heard, since this type of headset often fits very tightly against the ear and is designed to be soundproof. To hear himself or herself, the participant again attempts to speak very loudly, which leads to the disadvantages described above.
As described, ambient noise can also be picked up by a participant's voice microphone and transmitted via the conference system or a telephone system to other participants. A solution to this problem has already been developed for headsets in the mobile communications field, using two directional microphones, for example, arranged in opposite directions (toward the mouth/away from the mouth). The signal-to-noise ratio of the transmission signal is also improved there by compensating for the ambient noise. In this case, the other participants no longer hear the background noise as loudly. However, the participant is still subjected to the loud environment, and the other participants cannot tell that the speaker is speaking so loudly to overcome the ambient noise, and that this person may still have problems following along with the conference due to disruption from the loud ambient noise.
There is also another problem with a headset. Many headsets are designed for the earpiece to form a soundproof seal to block out the ambient noise. This also makes it necessary to remove the headset to interact with one's surroundings. The headset is also disruptively large. This means that a compromise must be made to acoustically seal the earpiece so the desired signal does not have to be amplified very strongly, since this amplification is energy-intensive and comes at a cost of battery life. In addition, it is also common here to output the ambient noise with a 180° phase shift, i.e., inverted, which causes the ear to cancel out the ambient noise.